COLUMBUS, Ohio (AP)  As Salvador Rendon was being arraigned last year on charges he had engaged for years in sexual intercourse with dogs, animal-rights activists descended on Warren, Ohio, to make their case: The state needed an anti-bestiality law.

The group had endured years of chiding: giggles about farm animals, “Deliverance” jokes, barks during a legislative hearing, questions of, “If the animal’s not injured, what’s the harm?”

But the Warren case was changing things.

Rendon was accused of having intercourse with two dogs  a male and a female boxer that belonged to his daughter  at least 10 times over a six-year period. Police told a local television station they’d “never seen a case like this one.” The judge called Rendon’s actions “despicable and highly disturbing.”

But, in a state where bestiality wasn’t a crime, authorities were limited to charging Rendon with animal cruelty, a misdemeanor, and only after proving he had caused physical harm to an animal. Rendon spent 30 days in jail and remains on five years’ probation.

The case prompted Warren to pass Ohio’s first local bestiality ban, with tougher penalties and no requirement to prove physical harm, allowing investigators to rely on witness testimony and forensic evidence. It also helped pass a statewide anti-bestiality law effective this month.

Eight states and the District of Columbia still lack anti-bestiality laws. Some states inadvertently lifted earlier prohibitions on human-animal sex when they were updating their laws to remove sodomy as a crime.

The Humane Society of the United States led the lobbying effort to outlaw bestiality, but a much larger coalition, including domestic violence shelters, conservative Christians, law enforcers and psychologists, got behind the law this time.

“We were able to explain that this is not just an animal issue,” said Corey Roscoe, the society’s Ohio state director. “This did have ramifications for human violence. Sexually deviant acts are a red flag to other acts of sexual violence.”

Since 2005, arrests for animal sex abuse and exploitation in the U.S. have risen dramatically. The number of arrests in 2014 was more than double the total number of arrests in the 30 years between 1970 and 2000.

Jenny Edwards, a criminologist in Washington who studies the issue, said the rise has been driven by the internet.

Online forums that exist behind powerful firewalls allow like-minded people to communicate and share animals for breeding and sexual experiences.

“It’s been great for deviants,” Edwards said.

A decade of research by Edwards also shows links between those who abuse animals and those who abuse other vulnerable groups, including children, women and other family members.

Animals involved are mostly horses, large dogs and sometimes deer. Roscoe said large animals are targeted in part because physical harm is more difficult to prove if perpetrators are caught. Psychologists have testified animals suffer psychological effects, including depression, anxiety and aggression.

The Federal Bureau of Investigation singled out animal cruelty offenses in its national crime statistics for the first time last year, in an effort to begin to definitively quantify the problem.

Edwards said such crimes are difficult to track, because the animals involved are often shuffled off to shelters without being tested for abuse, because police departments are focused on human crimes, and because veterinarians often don’t know what to look for. She advises using human rape kits.

Stigma remains an obstacle.

Though she supported the vote, Warren City Council member Helen Rucker, a Democrat, raised concern that passing the state’s first law would suggest the city had a widespread problem. Until the latest bill, championed by a pair of Republican state senators, Ohio legislators hesitated to put their names on proposed bestiality bills, seeing the issue as a punch line advanced by some overly zealous animal lovers.

When Edwards called a North Carolina police department to report a bestiality case she’d uncovered, a detective put her on speaker phone so he and his colleagues could laugh.

“That’s a lot of what my work is focused on, trying to remove that idea,” she said. “It’s not a joke. It’s far more common than people realize it is, and far more sinister than people realize it is.”